Process for the manufacture of cellulose.



a full, clear, and exact description of the EINAR' MOBTERUD, or roni'annon, NEAR moss, NORWAY.

PROCESS FOR THE MANUFACTURE OF CELLUIJOSE.

N'o Drawing.

To all whom 'z't-ma y concern:

Be it known that I, EINA MORTERUD, a

subject of the King of Norway, of Torderod, near Moss, Norway, have invented certain new andfuseful Improvements in Processes for the Manufacture of Cellulose; and I do hereby declare the: following to be invention, suchas willenable others skilled in the art to which it appertains to make and use thesame. r

This invention relates to the manufacture of cellulose according to the, sulfite method.

, be preheated to a C. Heating the ture 'involves the escape sustaining a pressure above that of the Even when this latter measure is made use of thesulfurous acid gas will 7 "a closed conduit in a gestion .liquid water,

. gestion operation or the like,-'which can be atmosphere.

In the manufacture of cellulose by digestin wood and other vegetable-matter in a su fite liquor, the digestion liquid cannot a temperature beyond. 40 liquid above this temperaof free sulfurous acid if' the liquid is not inclosed in a vessel however be expelled on passing digestion liquor from the said closed vessel through closed digester charged with wood chips. It is from this reason not practicable to preheat this diby the means now usually employed in connection with the-introduction of the required chemicals into the di gester.

According the v digestion liquidwhich has hitherto been used in the. form of a highly diluted solution of the required sulfurous acid compounds with sulfurous acid-is supplied to the digester in a muchhigher degree of concentration than hitherto employed and at such a low temperature .that the gas is retained therein. The deficiency in liquid may.then besupplied in the form /of pure ding di-- waste 'liquorfrom a prece heated to a high temperature without thereby undergoing 7 any chemical or physical ing normallya charge of 100 m with about 3 percent. free and about 1 per cent. combined sulfurous acid alteration. r

Supposing as anexample adigestertakof digestion l quid then this liquid cannot. be introduced into the 'digester' with a higher temperature than about 40 C. Supposing that a less quantity Specification of Letters Patent.

the material to be treated the supplied with astrong concentrated and;

to the present invention these difiiculties are overcome in the'manner, that Patented Apr. 8, i919.

Application filed December 6, 1918. Serial No. 265,553.v

- tained, viz., that a great deal of the required heat could be immediately imparted to the charge of thedigester, Hereby is also'obtained that the heat, which after a digestion operation is available for heating purposes, is utilized in a practical and economical manner as will be further explained in'the following.

The process according to this invention may for instance be carried into efiect in the following manner:

When the digester has been charged with comparatively cold digestion liquid in a quantity which stands ina reversed ratio to the relation between the concentration of the introduced digestion liquid and the concentration which it is'to have during the digestion operation. From a reservoir in which water or waste liquor is kept in a heated condition at a suitable elevated temperature and digester is then supplied with no a quantity of dilution liquid 'thatthe digestion digester is under asuitable-pressure the liquid attains a suitable concentration. The

in the usual'manner. When this operation is finished the digester is connected with the reservoir referred to, which in the meantime has been charged with cold water'or cold waste liquor, and the hotases steam and liquid is blown from the ig'ester into the reservoir, the necessary heating of the liquid contents of the same being thereby effected.

When the digestion operation is carried out in the manner hitherto employed a mixture of gas and vapor escaping from the digestion operation is then carried into efl:'ect

finished batch has to'be cooled before the gas is introduced into the acid plant for absorption and preparation of fresh d1- gestion liquid. A great by wasted. According to the present invention however this heat is now utilized to' preheat digestion liquid for the next di deal of heat is here-' gestion operation. As a consequence of this measure a saving-in apparatus is also 0btamed-the Whole large cooling plant for the escaping digester gas and steam being dispensed With.

I claim. I

1. Process for the manufacture of cellu- 'lose according to the sulfite method comprising the measures of introducing the chemicals required for the digestion opera tion in a degree of concentration higherthan required for the digestion operation and of introducing dilution liquid into the digester in the form of preheated Water, Waste digestion liquor or other liquid in the quantity E. MORTERUD.

to obtain the desired acid -con WVitnesses D. Voss, EINAR W.'DIESURUD. 

